Fracture analysis of finite length angle-ply composite double cantilever beam specimens

Abstract

The double cantilever beam specimen is assumed as two finite length beams, connected together, except at the initial delamination length. The energy release rate ( GI) is evaluated analytically by considering a Timoshenko beam on Winkler and Pasternak elastic foundations. The current data reduction methods have a blind spot in calculating GI when crack approaches the end of the ligament, which is considered in this study and, therefore, the simplifying assumption of infinite ligament length is not assumed here. GI will be strongly dependent on the ligament length if it is less than twice the thickness. Furthermore, the R-curves of different layups including their first points (fracture toughness) are drawn using Ρ–δ curves reported in the literature and they are compared to the experimental results. These comparisons show that Timoshenko beam on Winkler foundation gives the best results in comparison with experimental results for unidirectional and angle-ply laminates.